The Connecticut College Arboretum web site has information about plants native to the Northeastern U.S., including a link to a document listing native platns and the nurseries that sell them. They also sell many native species at their annual Fall Plant Sale.
The Georgia Native Plant Society web site has information about the Society's acitivities as well as links to regional sources for native plants.
The Maryland Native Plant Society has a lot of good links on its web site to check out, plus is very active in the field. If you from other parts of the country, they have a page that links to sites that list all native plant societies and other helpful information.
The Massachusetts Native Plant Committee web site has links to other local native plant organizations and a great list of native plants to use in your garden, organized by planting environment.
The Native Plants Network has information about propagation techniques and a link to the Native Plant Journal website.
Buy wildflowers native to the New England area from April through September at the New England Wildflower Society's Native
Plant Nursery. Seeds can typically be ordered through mid-March. Their big annual plant sale is June 7, 2003.